use of 3d/4d ultrasound in the evaluation of fetal anomalies

Conditions: Homozygous αº-thalassemia; Hb Bart's Disease

Summary: volumetry measurements can be a potential clinical use as non-invasive tools in prenatal diagnosis and screening and helps to reduce the risk and complications of invasive procedures. 3dus volumetry gives more precise results than 2dus volumetry measurements, particularly, of irregularly shaped objects.

conventionally volume measurements can be made by using multiplanar or vocaltm (virtual organ computer-aided analysis). recently, a new technique, xi vocaltm (extended imaging vocal) has been described. combined with the inversion mode, measurements for the liquid-filled structures can also be made. the potential use in clinical diagnosis and prediction of pathologies of volume measurements particularly in the first trimester are yet to be investigated. 3d ultrasound is found to be superior to 2d parameter in volumetry measurement. however, currently, there are still very few studies done to evaluate the potential use of volumetry measurement in clinical practice, especially of the validity and reproducibility of xi vocaltm; and the variation of results obtained within different ultrasound machines. due to the potential use of volumetry measurements in clinical practice, the accuracy in volumetry measurement is very important and the development of new technique need to be fully explored so that its benefits can be fully used for the contribution of clinical practice. so far no research has been done to evaluate the difference in the results obtained between different ultrasound machines, in particularly for volumetry measurements. this is important because if there is no significant difference in results between difference machines, we can accumulate the results from these machines for a study, which can include a more variety of samples. furthermore, it will be much easier to compare results of one machine with another for similar studies. both voluson 730 and accuvix have been used widely in research studies on 3d volumetry but comparison of the results obtained from these two machines have not been done. we do not know whether the results generated from one machine can be extrapolated to the other machine for clinical or research purpose. thus more research needs to be done in this area. thus, this study is carried out to evaluate the potential use of the new modality of xi vocaltm in the volumetry measurement of regular and irregular shaped objects, comparison of results obtained between different widely used machines, and the potential used of volumetry measurements in the prediction of common and important clinical pathologies such as αº-thalassemia.

Eligibility criteria:
inclusion criteria: for objective 1 and 2 - samples are recruited from our prenatal diagnostic clinic at ysan yuk hospital between 11-14 weeks' gestation. they are those who come for routine scan and those who are referred from the general antenatal clinics of the same hospital which pregnancies are at risk of homologous alphaº thalassaemia. for objective 3 - recruitment are the same as above except samples are obtained from normal pregnancy. for objective 4 - recruitment are the same as above. however, study is divided into intervention group and control group. for the intervention group, data is collected from pregnancies at risk of of homozygous αº-thalassemia while for the control group, data is collected from normal pregnancies. exclusion criteria: * if women refuse to participate in the study * patients with other co-existing illnesses

Keywords: 3d, 2d, ultrasound, volumetry, multiplanar, vocaltm, xi vocaltm, fetal, gestational sac, placenta